Callum’s regular Friday Fun on Ham Radio. Join in, see if you can hear me or just listen in. This is a hobby – so let’s have a laugh. 73. Callum.
Category: DX Commander
Callum’s Videos
I wonder if you can hear me? Join in the chat, listen in – or see if you can hear what I can hear? All for fun and games on Sunday. 73, Callum.
If you want me to build this. Let me know. However, in this video I explain the principles behind antenna design using Maxwell’s equations and the moment method starting with a simple vertical antenna, I demonstrates how we can predict resonant frequencies and also how we can make the antenna shorter while still maintaining its resonant frequency.
Then, let’s look at adding a coil to a vertical antenna, and how this affects the resonant frequency of the antenna’s harmonic – for instance how 7MHz is also resonant on 21MHz. Using a combination of the moment method (software simulation) and spreadsheet calculations, I’ll demonstrate how the position and value of the coil can change the antenna’s harmonic frequencies.
This video is a great resource for ham radio enthusiasts who are interested in understanding the technical aspects of antenna design and how to optimize their antennas for specific frequencies. Whether you’re a beginner or an experienced radio operator, you’ll find valuable insights and practical tips in this informative and engaging video.
In a nutshell, this isn’t an end-fed but a Dipole or a Vertical. I am VERY excited about this research. Can it be right? Using a loading coil to pull the 3rd harmonic for 21MHz down to 14.2MHz. Let me know what you think – then we can head out to the field and see if this works.
OK, we have enough for the next 100 Signature 9 DX Commander Antennas. Order now for delivery within a week or so. Buy here:
And have some fun!
Callum, Wendy and Loki.
Live again on Friday morning, 24th February 2023. See if you can hear us, join in or just listen. It’s Friday Playtime! Callum.
There is this rumour going around that 2,000W amplifiers are a total waste of time. You are missing a HUGE point. The ability to handle high levels of output without overheating needs thinking about. So why settle for a low-powered gear that melts under the stress of continuous-duty modes like FT8 or and RTTY? I happen to love my Acom 2000 for the durability and performance.
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The Fun I Have With Ham Radio
Let’s play ham radio, my science hobby. It’s fun to participate in and discover the joys of radio. Call in, join in the chat – or just listen. It’s up to you. All welcome.
Quick skim over building the Pre-Production Signature 9. The 10m element MIGHT change in the future, as an option to achieve very slightly better gain on 10m. Else, this is the cut chart:
If you are reading this line, then the User Guide is still under review – so run with these numbers please:
CUT CHART (that means *CUT* the wire to this length below – don’t ADD on the loops etc to the cut)
Band / Cut (in metres) [intermediate tensions use up this much in cm]
* 40 – 11.55m [there are two tension loops as discussed – they use up 10cm + 10cm]
* 30 – 7.94m [there are two tension loops as discussed – they use up 10cm + 10cm]
* 20 – 5.78m the foldback is 1.05m
* 17 – 3.96m assumes foldback is 6cm
* 15 – (as 40m)
* 12 – 2.83m assumes foldback is 6cm
* 10 – 2.5m assumes foldback is 6cm
To clarify: For instance with 40m, CUT to 11.55m. Same with 20m, just cut your wire to 5.78m. This caters for tension loops and foldbacks.
QRO: 10m foldback. See the User Guide for QRO modification on 10m band, ujsing a closed loop system.
I explore how I re-designed the CB / 11m SkyLab StarDuster and made a 15m / 12m and 10m high-gain powerhouse using the technique of off-centre-feeding, I show how I unlocked three-band performance from a single element. Discover how shared radials and element placement can make all the difference for any ham radio setup. Join me as I dive into the science behind off-centre-feeding and learn how to transform your antenna into a multi-band special! Don’t miss this exciting episode 🙂
More from this series
https://youtu.be/R2QNvcI08hU – The Design
https://youtu.be/V8Qq4-0_TjQ – The Build
More Videos:
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7zFt6NV9fnnde2lP11fUTQ8 Antenna Modelling
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7xtKohJRipVLQ6rxYzRP8eq Tips and Tricks
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7xwhA0Msm_bNT4CQ_Bj5D4c Antennas
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7wc6svNLY7IDthw1YCFNq9W Live Streams
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7w9dp9Eqg_UhamrY5Ck3dyX My Stuff
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7xvc3rHlpqqCkiBdAzYe8cf Ham Radio Training
Unlocking the secrets of walkie talkie and HT range testing with my latest video. Discover why these devices are mosttly reliable at under 500 metres, and how factors like a clear line of sight as well as elevation (say on a hilltop) can increase or degrade performance. Join us as we examine the science behind walkie talkie antenna gain, and see some real-time software modeling of range on a real map.
Featuring (Retevis RB639) – here’s Fred’s video: https://youtu.be/jJCW5Y8XzgE
Experience tells us that walkie talkies are mostly reliable at around 500 metres. However, sometimes you can get a greater range, for instance if you are in the clear or on top of a hill. We look at why this is, the software used to check the gain and we can even model the range over a live map. Tune in to understand.
The supplier tells me there is a deal here.. Here they are:
2 Pcs: https://www.amazon.co.uk/dp/B0BDR5XG63?maas=maas_adg_BE6878F5B1A200D1F6BECE0066CE7910_afap_abs&ref_=aa_maas&tag=maas
4 Pcs: https://www.amazon.co.uk/dp/B0BDR7B4CV?maas=maas_adg_859E1348AA707250CD6165B81C07E077_afap_abs&ref_=aa_maas&tag=maas
10 Pcs: https://www.amazon.co.uk/dp/B0BDR8HQSJ?maas=maas_adg_AB6D41AF606952928FA229BAD8B32693_afap_abs&ref_=aa_maas&tag=maas
More videos:
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7zFt6NV9fnnde2lP11fUTQ8 Antenna Modelling
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7xtKohJRipVLQ6rxYzRP8eq Tips and Tricks
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7xwhA0Msm_bNT4CQ_Bj5D4c Antennas
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7wc6svNLY7IDthw1YCFNq9W Live Streams
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7w9dp9Eqg_UhamrY5Ck3dyX My Stuff
▶️ https://youtube.com/playlist?list=PLcC64tNkZB7xvc3rHlpqqCkiBdAzYe8cf Ham Radio Training